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<p class="MsoNormal">Some background…<o:p></o:p></p>
<p class="MsoNormal">We use AMI and AsyncAGI to be able to receive events about calls (and other Asterisk details) and control it from our application.<o:p></o:p></p>
<p class="MsoNormal">Works great and have about 100 sites (some newer, some older) without issues.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I was notified this morning about a customer who had something strange happen and I can’t explain it.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Asterisk 16.23.0 and PJSIP.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Call comes into Asterisk.<o:p></o:p></p>
<p class="MsoNormal">Asterisk sends the Trying.<o:p></o:p></p>
<p class="MsoNormal">Via AMI, notified of the call and dial plan has it go to AsyncAGI for our application to be able to control the call.<o:p></o:p></p>
<p class="MsoNormal">Via AMI, we tell Asterisk to Answer.<o:p></o:p></p>
<p class="MsoNormal">Asterisk processes it and indicates it was answered.<o:p></o:p></p>
<p class="MsoNormal">The Asterisk AMI/AGI indicates call was answered successfully, call state is Up, etc.<o:p></o:p></p>
<p class="MsoNormal">Everything appears to be normal.<o:p></o:p></p>
<p class="MsoNormal">We perform various actions on the call, example play a file, music, tones, etc.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">However, Asterisk never sent the 200 OK to answer the call.<o:p></o:p></p>
<p class="MsoNormal">Seems as though Asterisk is in a bizarre state where it thinks it is handling the call, but it really isn’t.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Reports are this happened to several calls.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Eventually, they restarted the entire VM and everything started working well.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We think this may be caused by something their switch is doing.<o:p></o:p></p>
<p class="MsoNormal">Through the grapevine, heard they had some network issue but don’t know the details of their switches and architecture for calls coming into Asterisk.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We noticed we are seeing two INVITEs happen with the same Call-ID, but 2 additional Record-Route header/value pairs and 3 additional Via header/value pairs. At least in first glance, the rest seems to be the same. I see Asterisk created
two different PJSIP calls for each despite same Call-ID, but I am guessing that’s because of the additional Via or Record-Route pairs.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is it possible multiple of these double INVITEs could cause Asterisk or PJSIP on this older software to get into a bad state to cause the issues with AMI and Asterisk state?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Dan<o:p></o:p></p>
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